1.
Q: What's the difference between "lumens" and "lux"?A: Lumens measure the total amount of light output from a particular source. Lux measures the intensity of the light hitting a specified area. For example, an ordinary household lightbulb generates about 1000 lumens, but the intensity of its light at a particular point, such as on a book you're reading, will be comfortably low. Almost all flashlights rely on an optical device such as a reflector or lens to squeeze most of their output into a small area, which allows you to illuminate a point of interest with enough intensity, but without requiring a lot of power. To illustrate this concept, try the following: First, look at your room's ceiling light. In all likelihood, you can stare at it without much discomfort. Now, try looking into a weak flashlight like a traditional incandescent Mini-Maglite. You'll notice that it seems very bright. This is lux. Now, remove your Minimag's head to put it into candle mode. Try switching between its output and your ceiling light's output. Since they're now illuminating approximately the same area, the much higher lumen value of the ceiling light will provide much higher lux values at a chosen point. An extreme example of high lux and low lumens is a laser, which doesn't really create that much light, but focuses it into a tiny, brilliant point.

2.Q: What are "CCT" and "CRI"?A: CCT stands for "Correlated Color Temperature" and CRI stands for "Color Rendering Index." CCT is expressed in terms of degrees Kelvin, corresponding to the temperature of a black-body radiator (such as the Sun) at that color temperature. For example, a black-body radiator heated to about 8,000 degrees Kelvin would appear slightly bluish, so a light (an MH HID, for example) with a CCT of 8000K would have a bit of a bluish tint to it. CRI is expressed as a number from 1-100 and refers to how well a light source reveals colors regardless of its CCT. For example, a power LED that creates blue light that is filtered through a yellow phosphor to end up with white has no red component, leaving red and yellow objects slightly faded. This will lead to a low CRI rating. Incans, on the other hand, generally have a CRI of around 100, as they emit all spectra of visible light (as well as IR and UV light).

3.Q: What's "anodizing"?A: Anodizing is a process that oxidizes a surface (usually aluminum) and gives it a hard, wear-resistant coating. Many lights are Type II anodized, which means that they're reasonably resistant to wear. Type III anodizing, also known as Hard Anodizing, or HA, is very wear-resistant. Some lights are hard-anodized to military specifications, which is then called Mil-Spec HA.

4.Q: What are bezel-up and bezel-down carry?A: When a flashlight has a pocket clip attached at the tail end, it is carried with the head facing down. When it is attached near the head, the flashlight is carried with the head pointing upwards. Holsters can also be bezel-up or bezel-down. Some holsters depend on holding a flashlight bezel-up so that the large head prevents the flashlight from falling. One common example of this is the simple Maglite ring holster, in which the light's body goes through a ring that the head is too large to fit through, providing a simple bezel-up retention method. Other holsters depend on bezel-down carry, and still others can hold a flashlight bezel-up or bezel-down. This is similar to the point-up or point-down debate with knife carry.

5.Q: What methods are there for holding a flashlight?A: First is the overhand or "icepick" method, so named because it looks like the user is holding an icepick. The light is held somewhere above the user's shoulder. It's most useful for lights with a switch in the tailcap and is slightly more "tactical" than the underhand method, which is held near the waist and is useful for lights with side-mounted switches. Some lights, like Maglites, can be comfortably held either overhand or underhand. The Rogers-Surefire technique is a very specialized grip where a small flashlight's body is lodged between two fingers and the tailswitch (usually some sort of momentary one) rests in the palm. For users with a handgun in their other hand, both hands can be held side by side in a strong, stable manner.

6.Q: Where does a classic 2AA Minimag fit in?
A: A Minimag uses alkaline cells to drive an incandescent in an unregulated fashion. It has candle mode and tailstand capabilities. It produces about ten lumens, with output falling sharply and turning orange-yellow within about half an hour. The bulb and battery are both old technology, and both runtime and output suffer as a result, with most modern lights (in its class) delivering much greater runtime, output, or both (not to mention any other improvements).

7.Q: What is Fenix's naming scheme?A: [The following info was contributed by CPF's Gunner12.]

0 = 1 AAA powered, for the E series, 1 5mm LED, currently the Nichia CS, all twisties.
01 = 1 AAA powered, E series, multicolor anodizing, 1 5mm Nichia GS. 1 AAA powered LD series. Cree XR-E Q5 and three modes only, medium-low-high. Reflector is also improved and PWM is faster.
1 = 1 battery, for the E series, 1 Nichia Power LED, for the P series, a twistie. For the T series (T1) a 2 stage forward clickie light powered by 2 CR123 or RCR123 batteries with a clip. Uses a Cree XR-E Q5 LED in a textured reflector. Built to have thicker walls then the E and L series lights.
2 = 2 battery powered or for the P series, 1 CR123 with a clickie
3 = For the P series 2 CR123 powered
K10 = TK10, an "improved" version of the T1 with a removable grip ring, aluminum bezel, and removable clip. Performance is not changed. --- LD10 "improved" version of the L1D. Look at LD to see what improved over the L1D.
K11 = TK11, an "improved" version of the TK10 and T1 with a smooth reflector and the ability to accept 18650 batteries.
K30: Part of the T series, multimode controlled by a ring that is twisted to adjust output (low, medium, high, strobe), 3 CR123, crenellated bezel, smooth reflector, clickie.
K40: Part of the T series, Fenix's first multidie LED flashlight, has a Cree MC-E in a textured reflector powered by 8 AA batteries but can use 4 in an emergency, 2 modes of output, first mode is turbo, low, medium, and high, second mode is strobe, slow flash, SOS, fast flash, clickie.
20 = T20 or LD20 or PD20 --- T20 is a 2AA-powered light similar to the other T series but has a neutral white LED instead of a cool white one. Has a smooth reflector, a rubber sleeve on the body tube for grip, and a removable clip. --- LD20, "improved" version of the L2D, adding body knurling. Look at LD to see what changes were made over the L2D. --- PD20, "improved" version of the P2D. Look at PD to see what changed.
30 = PD30, "improved" version of the P3D. Look at PD to see what changed.

If there is a thing after the CE, that is to designate the Bin of the Cree XR-E LED used. Q5 means it uses the Cree XR-E Q5 LED. No designation after the CE means it uses the P3 or P4, depending on date of manufacturing.

The Civictor V1 is a 1 AA twistie with Type II anodizing. There was a multimode stainless steel model made.

There was a special Titanium version of the L0D made. It was called the L0D Ti. There was also a Christmas version(red type II anodizing with Christmas decorations) called the L0D SE. There is also a Q4 version.